Iron-aluminum alloy and preparation method therefor

ABSTRACT

Disclosed are an iron-aluminum alloy and its preparation method. The iron-aluminum alloy comprises, by weight, 50% to 80% of iron and the balance of aluminum. The method comprises: adding metal aluminum or molten aluminum to a container, wherein the temperature of the molten aluminum is between 700° C. and 800° C.; adding a metal iron raw material to the molten aluminum, closing a furnace cover, measuring the pressure, and introducing argon to ensure that the interior of a magnetic induction furnace is in a positive-pressure state, and stirring the mixture with a graphite stirring head; powering on and heating so that the metal aluminum or the molten aluminum is heated to 1000° C. or above and molten, and holding the temperature between 1000° C. and 1500° C.; and after alloying is completed, cooling to about 1000 t, opening the furnace cover, and taking the iron-aluminum alloy out.

BACKGROUND OF THE INVENTION 1. Technical Field

The invention relates to the technical field of iron-aluminum alloys and preparation thereof and in particular to an iron-aluminum alloy and its preparation method.

2. Description of Related Art

During the production and processing of aluminum alloy materials (such as aluminum plates for aviation, aluminum plates for cans, and aluminum plates for PS plate bases, etc.), it is usually required to add metal iron element to a molten aluminum melt (having a temperature generally controlled between 740° C. and 750° C.), so that the metal iron and aluminum form intermetallic compounds (i.e., aluminum-iron alloys) with a densely linked network structure, so as to significantly improve the physical properties of the aluminum products. However, since the melting point of metal iron is 1538° C., and the melting temperature of an aluminum melt is generally controlled between 740° C. and 750° C., in order to rapidly melt and blend metal iron into the aluminum melt and make the metal iron and aluminum form intermetallic compounds (aluminum-iron intermetallic compounds), at present, there are mainly the following methods available.

A first method is to add a calculated amount of an iron additive to an aluminum melt. This iron additive is made by thoroughly mixing, by a physical method, iron powder of certain meshes and mechanically broken potassium fluoroaluminate (KA1F₄, commonly known as PAF) together and pressing the mixture into cakes by virtue of a mechanical pressure (oil pressure, air pressure, etc.). Because the specific gravity of the cakes is higher than that of molten metal aluminum, after these cakes are put into the molten metal aluminum, under the fluxing action of PAF, the metal iron can be rapidly melted and bend into molten aluminum and form intermetallic compounds (alloys) with aluminum. However, since the main component of PAF contains fluorine (F), it causes environmental pollution due to the volatilization and cleaning (refining) of fluorine (F) in the production process.

A second method is to replace the fluxing agent KA1F₄ with aluminum powder. Since the aluminum powder will burn at 740° C. to produce aluminum oxide and generate a large amount of heat simultaneously, the heat generated by the burning of the aluminum powder can promote the rapid melting and blending of iron powder into the aluminum melt and causing the metal iron in the aluminum melt and aluminum to form alloys (intermetallic compounds). However, since the aluminum powder is completely oxidized into aluminum oxide after the burning and heat release in the whole process, the aluminum oxide will partially enter the molten aluminum, which has a negative effect on the purification of the aluminum melt. Moreover, due to the high cost of aluminum powder, the aluminum oxide produced after complete burning can only be get rid of as slag in the smelting process, which increases the production cost.

In order to solve these technical problems, at present, in the processing of aluminum alloy materials (various types, various types of plates, various types of bars, etc.), a calculated amount of an iron element additive (commonly known as an iron additive) is usually added to the molten aluminum with a temperature between 740° C. and 750° C., to increase the strength of the aluminum product produced. The common specifications of iron additives currently used are 70 iron agents (Fe: 70 wt %), 75 iron additives (Fe: 75 wt %), 80 iron additives (Fe: 80 wt %), 85 iron additives (Fe: 85 wt %), and the like. At present, the following two methods are usually used to produce iron additives.

1. Iron powder of certain meshes and PAF powder of certain meshes are thoroughly mixed and then pressed into cakes by mechanical means through combination of a pressure and a mold. The specific gravity of the cakes should be higher than that of aluminum melt to ensure that the cakes can sink into the aluminum melt during the addition process and avoid being oxidized by air as much as possible.

2. Aluminum powder of certain meshes and iron powder of certain meshes are mixed thoroughly and then pressed into cakes by mechanical means through combination of a pressure and a mold. The specific gravity of the cakes should be higher than that of aluminum melt to ensure that the cakes can sink into the aluminum melt during the addition process and avoid being oxidized by air as much as possible. In the cakes, by weight, the iron powder accounts for 70%, 75%, 80%, 85%, or the like, and the aluminum powder accounts for 30%, 25%, 20%, or 15%. These iron additives may also be commonly known as 70 iron additive, 75 iron additive, 80 iron additive, 85 iron additive and so on in business.

According to the production methods of these two iron additives, the products obtained are physical mixtures of iron and aluminum or iron and PAF. When the physical mixtures are added to molten aluminum as iron additives, to improve the strength of the produced aluminum produce, intermetallic compounds (aluminum-iron alloys) can only be completely formed after two steps. The first step is the dissolution process of elemental iron in molten aluminum; the second step is the alloying (for forming intermetallic compounds) process of metal iron dissolved in the molten aluminum and aluminum. The implementation of these two processes has the following defects:

1. During the process, elemental iron may be oxidized by oxygen in the air to form iron oxide and float on the surface of molten aluminum, which affects the absorption rate of metal iron in the smelting process.

2. The process of causing the metal iron successfully dissolved into molten aluminum and aluminum to form intermetallic compounds and weaving into dense network-like reinforcement phases. The completeness of this process will affect the strength and quality of the aluminum material due to improper or insufficient time control in the smelting process.

BRIEF SUMMARY OF THE INVENTION

The main objective of the invention is to provide an iron-aluminum alloy and its preparation method, in order to achieve a solution where iron and aluminum in an iron-aluminum alloy are first alloyed fully and the alloyed product is then used as an iron additive to replace a current popular iron additive and added to molten aluminum as an iron additive during the smelting process. Compared with the current popular iron additives, this product has better absolute absorption rate and speed of elemental iron, and can eliminate the pollution caused by fluorine to the environment and improve the physical properties of the aluminum product produced.

In order to achieve the above objective, the invention provides an iron-aluminum alloy. The iron-aluminum alloy is composed of metal iron and aluminum and includes, by weight, 50% to 80% of iron and the balance of aluminum.

The iron-aluminum alloy is an intermetallic compound formed by metal iron and metal aluminum at a high temperature.

The iron-aluminum alloy can be amorphous blocks, flakes or powder. Regardless of blocks, flakes or powder, their specifications can be restricted by formulating corresponding standards.

In order to achieve the above objective, the invention further provides a preparation method of an iron-aluminum alloy. The method includes the following steps:

Step S1, adding metal aluminum or molten aluminum into a container, wherein the temperature of the molten aluminum is between 700° C. and 800° C.;

Step S2, adding a metal iron raw material (iron powder, iron flakes, iron filings or iron blocks, or a mixture of one or more of iron powder, iron flakes, iron filings and iron blocks) into the molten aluminum, closing a furnace cover, carrying out vacuumization, introducing argon, measuring temperature, and measuring pressure to ensure that the interior of a magnetic induction furnace is in a positive-pressure state, and stirring the mixture with a graphite stirring head;

Step S3, powering on and heating so that the metal aluminum or the molten aluminum is heated to 1000° C. or above and molten, and holding the temperature between 1000° C. and 1500° C., wherein the metal aluminum and iron form an intermetallic compound in this process and the time of the alloying process is between 30 min and 2 h; and

Step S4, after alloying is completed, cooling to about 1000 t, opening the furnace cover, and taking the iron-aluminum alloy out.

As a further technical solution of the invention, the container is a crucible placed in a vacuum magnetic induction furnace, or a crucible placed in a vacuum resistance furnace, or a non-vacuum container with a protective flux.

As a further technical solution of the invention, a frequency of the induction furnace ranges from 800 Hz to 1200 Hz.

As a further technical solution of the invention, the metallic iron raw material is iron powder, iron flakes, iron filings or iron blocks, or a mixture of one or more of iron powder, iron flakes, iron filings and iron blocks.

As a further technical solution of the invention, in Step S3, the time of stirring with the graphite stirring head is within a range of 0.5 h to 2 h.

As a further technical solution of the invention, the production method of the iron-aluminum alloy includes but is not limited to a production process using a vacuum magnetic induction furnace, a production process using crucibles lined with different materials in a vacuum resistance furnace, and other heating production processes where in a non-vacuum way, a suitable protective flux or fluxing agent is selected to isolate the air.

As a further technical solution of the invention, subsequent to Step S4, the method further includes:

casting the iron-aluminum alloy into various types of blocks or flakes or breaking the same into powder with different diameters as required, and adding the iron-aluminum alloy as an iron element additive to a smelting and preparation process of an aluminum alloy material to improve the physical properties of the aluminum product produced.

The beneficial effects of the iron-aluminum alloy of the invention and its preparation method are as follows:

Compared with the existing products, the iron-aluminum alloy prepared by the invention contains iron and aluminum which are fully and completely alloyed. Comparison with existing iron additives used in the production of aluminum products to increase the strength, this fully alloyed iron-aluminum alloy is no longer a physical mixture of aluminum powder and iron powder, nor is it a physical mixture of iron powder and potassium fluoroaluminate (commonly known as PAF). This iron-aluminum alloy is used as an element additive for metal iron in the aluminum production process to replace the currently popular iron additives (one type is a cake-like substance formed by pressing, by virtue of a pressure, metal iron powder and PAF powder which are thoroughly mixed in a certain proportion in a physical manner; the other type is a cake-like substance formed by pressing, by virtue of a pressure, metal iron powder and metal aluminum powder which are mixed in a physical manner. Compared with the currently popular iron additives, this iron-aluminum alloy has the following four major advantages.

1. The invention solves the problem of environmental pollution (fluorine pollution) caused after a smelting and dissolution process where using PAF as a fluxing agent, metal iron enters into an aluminum melt to form an intermetallic compound with metal aluminum.

2. The invention solves the problem of pollution (aluminum oxide inclusions) to an aluminum alloy melt after a melting and dissolution process where using aluminum powder as a heat generating agent (the high heat generated by the oxidation process of aluminum powder takes a fluxing effect in the alloying of iron), metal iron enters into an aluminum melt to form an intermetallic compound with metal aluminum.

3. The iron-aluminum alloy which is a basically formed intermetallic compound serves as an iron element additive. When added to the aluminum melt, the iron-aluminum alloy functions in the aluminum melt to diffuse and form a dense network-like alloyed intermetallic compound, instead of first forming an intermetallic compound and then diffusing into a network. Therefore, In the same time of smelting with addition of iron additives, the strength and quality of an aluminum product produced by use of the iron-aluminum alloy as an iron element additive and the purity of the aluminum product are much higher than the quality of aluminum products produced by use of the above-mentioned first and second types of iron additives.

4. Compared with iron additives (pressure-processed physical mixtures of iron powder and PAF and of iron powder and aluminum powder), the iron-aluminum alloy has better absolute absorption rate of metal iron in the addition process of aluminum smelting and physical properties of produced aluminum products.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diffraction pattern of AlFe50;

FIG. 2 is a diffraction pattern of AlFe55;

FIG. 3 is a diffraction pattern of AlFe60;

FIG. 4 is a diffraction pattern of AlFe70;

FIG. 5 is a metallographic diagram of AlFe20;

FIG. 6 is a metallographic diagram of AlFe50;

FIG. 7 is a metallographic diagram of AlFe55;

FIG. 8 is a metallographic diagram of AlFe60;

FIG. 9 is a metallographic diagram of AlFe70;

FIG. 10 is a metallographic diagram of AlFe80;

FIG. 11 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe20, the molten aluminum was 750° C. and the Fe content was controlled at 1%;

FIG. 12 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe50, the molten aluminum was 750° C. and the Fe content was controlled at 1%;

FIG. 13 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe55, the molten aluminum was 750° C. and the Fe content was controlled at 1%;

FIG. 14 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe60, the molten aluminum was 750° C. and the Fe content was controlled at 1%;

FIG. 15 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe70, the molten aluminum was 750° C. and the Fe content was controlled at 1%;

FIG. 16 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe80, the molten aluminum was 750° C. and the Fe content was controlled at 1%;

FIG. 17 is a schematic flow chart of a preferred embodiment of the preparation method of a iron-aluminum alloy according to the invention; and

FIG. 18 is a schematic structural diagram of a magnetic induction furnace.

DETAILED DESCRIPTION OF THE INVENTION

It should be understood that the preferred embodiments described here are only for explaining the invention rather than limiting it.

In order to achieve full alloying of iron and aluminum in iron-aluminum alloys, improve the iron absorption rate and speed of iron-aluminum alloy additives in the processing of iron-aluminum alloy profiles, and reduce environmental pollution, the invention provides an iron-aluminum alloy. The iron-aluminum alloy is composed of aluminum and iron and includes, by weight, 50% to 80% of iron and the balance of aluminum.

The weight percentage of the iron can be, for example, 50%, 55%, 60%, 70%, and 80%, and the corresponding iron-aluminum alloy can be expressed as AlFe50, AlFe55, AlFe60, AlFe70, and AlFe80.

It can be understood that the iron-aluminum alloy of the invention is mainly used as an additive of elemental iron in the production process of aluminum alloy profiles. It should be specially pointed out that the impurities of this iron-aluminum alloy product should be limited, for example, the content of iron and silicon should not be greater than 0.5%, and the combined content of aluminum oxide and iron oxide should not be greater than 0.5%.

The iron-aluminum alloy is an intermetallic compound formed by metal iron and metal aluminum at a high temperature.

The iron-aluminum alloy can be amorphous blocks, flakes or powder. Regardless of blocks, flakes or powder, their specifications can be restricted by formulating corresponding standards.

In this embodiment, when metal iron and metal aluminum are melted at a high temperature, an intermetallic compounds AlFe3, Al5Fe2, AlFe and elemental Fe are formed. For the phase diagrams of iron-aluminum, reference can be made to FIGS. 1 to 4 .

FIG. 1 is a diffraction pattern of AlFe50;

FIG. 2 is a diffraction pattern of AlFe55;

FIG. 3 is a diffraction pattern of AlFe60; and

FIG. 4 is a diffraction pattern of AlFe70.

In this embodiment, the metallographic diagrams of different types of AlFe alloys refer to FIGS. 5 to 10 .

FIG. 5 is a metallographic diagram of AlFe20;

FIG. 6 is a metallographic diagram of AlFe50;

FIG. 7 is a metallographic diagram of AlFe55;

FIG. 8 is a metallographic diagram of AlFe60;

FIG. 9 is a metallographic diagram of AlFe70; and

FIG. 10 is a metallographic diagram of AlFe80.

In this embodiment, the metallographic diagrams of the processed aluminum alloys after different types of AlFe alloys are absorbed and the corresponding physical property indicators are shown in FIGS. 11 to 16 .

FIG. 11 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe20, the molten aluminum was 750° C. and the Fe content was controlled at 1%;

FIG. 12 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe50, the molten aluminum was 750° C. and the Fe content was controlled at 1%;

FIG. 13 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe55, the molten aluminum was 750° C. and the Fe content was controlled at 1%;

FIG. 14 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe60, the molten aluminum was 750° C. and the Fe content was controlled at 1%;

FIG. 15 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe70, the molten aluminum was 750° C. and the Fe content was controlled at 1%; and

FIG. 16 is a metallographic diagram of an aluminum alloy at the magnification of 100×, 200×, and 500× after absorption for 60 min where the iron additive was AlFe80, the molten aluminum was 750° C. and the Fe content was controlled at 1%.

Referring to FIGS. 11 to 16 , it can be seen from the metallographic diagrams of the aluminum alloy material formed after the 80 iron additive was dissolved in 750° C. molten aluminum for 1 h that:

1. There is a small amount of incompletely alloyed elemental iron particles; and

2. Compared with the use of various aluminum-iron alloys (20, 50, 55, 60, 70, and 80), the use of the 80 iron additive lead to obvious differences in the distribution, arrangement and shape of aluminum-iron compound phases observed under a 500× microscope.

Table 1 shows the functional performance of 80 iron additive and various aluminum-iron alloys (20, 50, 55, 60, 70, and 80).

TABLE 1 Mechanical property Tensile strength Yield strength Elongation at (Mpa) Stirred (Mpa) Stirred break (%) Stirred for 1 h for for 1 h for for 1 h for Alloy type dissolution dissolution dissolution 80 iron additive 79.525 32.11 20.905 AlFe70 79.41 32.11 62.11 AlFe60 97.89 43.72 83.63 AlFe55 84.06 38.9 81.6 AlFe50 83.69 35.66 77.3 AlFe20 88.66 19.31 75.78

It can be seen from Table 1 that the functional performance (influence on the physical properties of the processed aluminum product) of AlFe20 is basically the same as that of the 80 iron additive, while the physical properties of AlFe60 have changed significantly.

Comparing FIG. 11 with FIGS. 12, 13, 14, and 15 , it can be seen from the metallographic diagrams that the arrangement of the aluminum-iron alloy compound phase of AlFe20 is significantly inferior to that of AlFe50, AlFe60, AlFe65, and AlFe70, and the alloy phases of AlFe50, AlFe60, AlFe65, and AlFe70 are denser, and the physical properties of the processed aluminum alloys are better.

Comparing FIG. 16 with FIGS. 12, 13, 14, and 15 , it can be seen that: 1. There are a small amount of incompletely alloyed elemental iron particles as show in FIG. 16 ; 2. Compared with various aluminum-iron alloys (20, 50, 55, 60, 70, 80) in FIGS. 16 , there are obvious differences in the distribution, arrangement and shape of the aluminum-iron compound phase observed under a 500× microscope.

Compared with the currently popular iron element additives, the iron-aluminum alloy of the invention has a significant change in the absolute iron absorption rate and physical properties during the smelting and processing of the aluminum alloy material, and especially for AlFe60, after its iron element is absorbed by the aluminum alloy, the physical properties of the corresponding aluminum product are particularly outstanding.

In order to achieve the above objective, the invention further provides a preparation method of the iron-aluminum alloy as described above.

Reference is made to FIG. 14 . FIG. 14 is a schematic flow chart of a preferred embodiment of the preparation method of an iron-aluminum alloy according to the invention.

As shown in FIG. 14 , in this embodiment, the preparation method of an iron-aluminum alloy includes the following steps:

In Step S1, metal aluminum or molten aluminum is added into a container, wherein the temperature of the molten aluminum is between 700° C. and 800° C.

The container can be the crucible 3 placed in the magnetic induction furnace as shown in FIG. 9 . The magnetic induction electric furnace includes a furnace cover 1, a magnetic induction furnace shell 2, a vacuumizing opening 5, a pressure measuring opening 6, an argon inlet 7, and a temperature measuring opening 8. The magnetic induction furnace shell 2 is made of an aluminum material. The outer periphery of the crucible 3 placed in the magnetic induction furnace is provided with a copper magnetic induction coil 4 (hollow, with cooling water inside). The crucible 3 can be a silicon carbide crucible, a graphite crucible, a clay crucible or a crucible for an induction furnace, made from other refractory materials formed by hammering ramming materials (such as quartz sand, magnesia, aluminum oxide, and the like) to hold the molten metal.

The frequency of the magnetic induction furnace can be selected from 800 Hz to 1200 Hz.

In other embodiments, the container can also be crucibles lined with different materials in a vacuum resistance furnace, or use other heating production processes where in a non-vacuum way, a suitable protective flux is selected to isolate the air.

In Step S2, a metal iron raw material is added into 700° C. molten aluminum, the furnace cover is closed, and then the operations of vacuuming, argon introduction, temperature measuring, and pressure measuring are carried out to ensure that the interior of the magnetic induction furnace is in a positive-pressure state, and the mixture is then stirred with a graphite stirring head.

In Step S3, the furnace is powered on for heating the metal aluminum or the molten aluminum to 1000° C. or above, the metal aluminum or the molten aluminum is molten and the temperature is held between 1000° C. and 1500° C., and for example, it can be 1000° C., 1250° C. or 1500° C., wherein the metal aluminum and iron form an intermetallic compound, i.e., the iron-aluminum alloy, in this process and the time of the alloying process is between 30 min and 2 h.

The metal iron raw material may be iron powder, iron filings, iron blocks, iron flakes or a mixture of one or more of iron powder, iron filings, iron blocks, and iron flakes.

In this embodiment, the time of stirring with the graphite stirring head may be set within a range of 0.5 h to 2 h according to actual needs, and for example, it can be 0.5 h, 1.25 h, or 2 h.

It can be understood that the time required for the entire alloying process is generally controlled within the range of 30 min to 2 h, which can ensure that metal iron and aluminum form an intermetallic compound as much as possible, thus obtaining a qualified fully alloyed iron-aluminum alloy and avoiding the generation of a small amount of metal oxides (iron oxide or aluminum oxide).

In Step S4, after alloying is completed, the mixture is cooled to about 1000° C. and the furnace cover is then opened to take out the iron-aluminum alloy.

In addition, as an implementation manner, subsequent to Step S4, the method may further include:

casting the iron-aluminum alloy into amorphous blocks or flakes or mechanically breaking the iron-aluminum alloy into a powder; and then accurately adding a calculated amount of the iron-aluminum alloy as an iron element additive to the smelting and preparation process of the aluminum alloy material. The iron-aluminum alloy can be amorphous blocks, flakes or powder. Regardless of blocks, flakes or powder, their specifications can be restricted by formulating corresponding standards.

The beneficial effects of the iron-aluminum alloy of the invention and its preparation method are as follows. Compared with the existing products, the iron-aluminum alloy prepared by the invention contains iron and aluminum which are fully and completely alloyed. Comparison with existing iron additives used in the production of aluminum products to increase the strength, this fully alloyed iron-aluminum alloy is no longer a physical mixture of aluminum powder and iron powder, nor is it a physical mixture of iron powder and potassium fluoroaluminate (commonly known as PAF). This iron-aluminum alloy is used as an element additive for metal iron in the aluminum production process to replace the currently popular iron additives (one type is a cake-like substance formed by pressing, by virtue of a pressure, metal iron powder and PAF powder which are thoroughly mixed in a certain proportion in a physical manner; the other type is a cake-like substance formed by pressing, by virtue of a pressure, metal iron powder and metal aluminum powder which are mixed in a physical manner. Compared with the currently popular iron additives, this iron-aluminum alloy has the following four major advantages.

1. The invention solves the problem of environmental pollution (fluorine pollution) caused after a smelting and dissolution process where using PAF as a fluxing agent, metal iron enters into an aluminum melt to form an intermetallic compound with metal aluminum.

2. The invention solves the problem of pollution (aluminum oxide inclusions) to an aluminum alloy melt after a melting and dissolution process where using aluminum powder as a heat generating agent (the high heat generated by the oxidation process of aluminum powder takes a fluxing effect in the alloying of iron), metal iron enters into an aluminum melt to form an intermetallic compound with metal aluminum.

3. The iron-aluminum alloy which is a basically formed intermetallic compound serves as an iron element additive. When added to the aluminum melt, the iron-aluminum alloy functions in the aluminum melt to diffuse and form a dense network-like alloyed intermetallic compound, instead of first forming an intermetallic compound and then diffusing into a network. Therefore, In the same time of smelting with addition of iron additives, the strength and quality of the aluminum product produced by use of the iron-aluminum alloy as an iron element additive and the purity of the aluminum product are much higher than the quality of aluminum products produced by use of the above-mentioned first and second types of iron additives.

4. Compared with iron additives (pressure-processed physical mixtures of iron powder and PAF and of iron powder and aluminum powder), the iron-aluminum alloy has higher absolute absorption rate and speed of metal iron in the addition process of aluminum smelting.

The above description is set forth only as preferred embodiments of the invention and is not intended to limit the scope of the invention. Any equivalent structure or equivalent process transformation, made on the basis of the contents of the description of the invention and the accompanying drawings and directly or indirectly used in other related technical fields, is likewise included within the scope of the patent protection of the invention. 

1. An iron-aluminum alloy, composed of metal aluminum and iron and comprising, by weight, 50% to 80% of iron and the balance of aluminum.
 2. A preparation method of the iron-aluminum alloy according to claim 1, the preparation method comprising the following steps: Step S1, adding a metal aluminum or a molten aluminum into a container, wherein the temperature of the molten aluminum is 700° C. to 800° C.; Step S2, adding a metal iron raw material into the molten aluminum, closing a furnace cover, carrying out vacuumization, introducing argon, measuring temperature, and measuring pressure to ensure that the interior of a magnetic induction furnace is in a positive-pressure state, and stirring with a graphite stirring head; Step S3, powering on and heating so that the metal aluminum or the molten aluminum is heated to 1000° C. or above and molten, and holding the temperature between 1000° C. and 1500° C., wherein the metal aluminum and iron form an intermetallic compound in this process and the time of the alloying process is between 30 min and 2 h; and Step S4, after alloying is completed, cooling to about 1000° C., opening the furnace cover, and taking the iron-aluminum alloy out.
 3. The preparation method of the iron-aluminum alloy according to claim 2, wherein the container is a crucible placed in the magnetic induction furnace, or a crucible placed in a vacuum resistance furnace, or a non-vacuum heatable container with a protective flux and a fluxing agent.
 4. The preparation method of the iron-aluminum alloy according to claim 3, wherein a frequency of the magnetic induction furnace ranges from 800 Hz to 1200 Hz.
 5. The preparation method of the iron-aluminum alloy according to claim 2, wherein the metal iron raw material can be iron powder, iron flakes, iron filings or iron blocks, or a mixture of two or more of iron powder, iron flakes, iron filings and iron blocks.
 6. The preparation method according to claim 2, wherein in the Step S3, the time of stirring with the graphite stirring head is 0.5 h to 2 h.
 7. The preparation method according to claim 2, subsequent to the Step S4, further comprising: casting the iron-aluminum alloy into various types of blocks or flakes or breaking the same into grains (including powder) with different diameters as required, and adding the iron-aluminum alloy as an iron element additive to a smelting and preparation process of an aluminum alloy material to improve the physical properties of the produced aluminum product. 